Grinder attachment for a lathe

ABSTRACT

A precision finishing tool for use in turning brake drums incorporates a plurality of different length quills and means for interchanging the quills for use with different sizes of rotors.

United States Patent [191 Mitchell Aug. 13, 1974 [5 GRINDER ATTACHMENT FOR A LATHE 1,464,728 8/1923 Ross 51/261 ,7 ll 9 H' [75] Inventor: wifllace Mllchell Arlmgto 5,452,21 7x923 xl l l 'j'luk 51/259 Heights, Ill. [73] Assignee: Ammco Tools, Inc., North Chicago, FOREIGN PATENTS B APPLICATIONS 11] 184,556 8/1922 Great Britain 5l/l6l [22] Filed: 1972 Primary Examiner-Othell M. Simpson [21] Appl. No.: 311,124 Attorney, Agent, or Firm-Edmond T. Patnaude [52] U.S. Cl. 51/259 57 ABSTRACT [51] Int. Cl B24b 19/26 58 Field of Search 51/259, 261, 170T A Preclslon fimshmg use tummg brake drums incorporates a plurality of different length [56] References Cited quills and means for interchanging the quills for use UNITED STATES PATENTS 2/1907 Dorris 5l/26l with different sizes of rotors.

6 Claims, 4 Drawing Figures GRINDER ATTACHMENT FOR A LATHE The present invention relates in general to grinding attachments for lathes, and it relates more particularly to a new and improved grinding attachment incorporating means for quickly and easily replacing the quill portion thereof.

BACKGROUND OF THE INVENTION In order to provide a smooth, even finish on the internal cylindrical brake surface of a brake drum, it is desirable to finish grinding the brake surface to level off any hard spots in the drum metal. For best results the grinding operation should immediately follow the turning operation without removal of the drum from the lathe spindle. Hence, the grinding attachment must be easily and quickly mounted to the lathe after completion of the turning operation.

Brake drums vary substantially in size from the very small drums used in compact type automobiles to the very large drums used in trucks. While the same lathe may be used for turning the entire range of drum sizes, grinder attachments for precision finishing of the brake surfaces have not been available for use with such a wide range of drum sizes.

Another problem with the prior art type grinder attachments has been the lack of uniformity of the finished brake surfaces which, I believe, resulted from the different ways in which the operators set up the lathe and from variations in the hardness of the drum metal.

OBJECTS OF THE INVENTION Therefore, a principal object of the present invention is to provide a new and improved grinder attachment for a lathe.

Another object of this invention is to provide a novel grinder attachment employing a universal power head and a plurality of interchangeable quills.

A further object of this invention is to provide a grinder attachment which provides a truer and more uniform surface finish than that provided with prior art type grinding attachments.

SUMMARY OF THE INVENTION Briefly, the above and further objects may be realized in accordance with the present invention by providing a power head including a constant speed, induction motor, a plurality of interchangeable quills, and a quick-connect-disconnect coupling for connecting the selected one of the quills to the power head. Each quill includes a tubular shaft driven by the power head and a relatively heavy spindle driven by the shaft and to which the grinding wheel is mounted.

BRIEF DESCRIPTION OF THE DRAWING Further objects and advantages and a better understanding of the present invention may be had by reference to the following detailed description taken in connection with the accompanying drawing, wherein:

FIG. 1 is a perspective view of the grinder attachment of the present invention mounted on a lathe for finish grinding a brake drum;

FIG. 2 is an exploded, cross-sectional view of a grinder attachment embodying the present invention;

FIG. 3 is a sectional view of the forward end portion of a quill taken along the line 3-3 of FIG. 2', and

FIG. 4 is a sectional view of the power head of the grinder attachment of FIG. 2 taken along the line 4-4 thereof.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, a grinder attachment 10 embodying the present invention is mounted on the crossfeed assembly 12 of a lathe 14 on the spindle of which is mounted a brake drum 16 having an internal, cylindrical braking surface 18. An abrasive grinding wheel 20 is mounted at the end of a quill assembly 22 which is tightly clamped in the crossfeed assembly 12 and to which a power head 24 is removably connected. After the braking surface 18 has been turned in the usual manner, the cutting tool assembly, not shown, is removed from the cross feed assembly 12 and replaced by the grinder attachment 10. With the grinding wheel 20 properly dressed, the cross-feed handwheel 26 is rotated to move the wheel 20 into engagement with the braking surface 18 and the lathe and power head are switched on to respectively rotate the drum [6 and the grinding wheel 20. The spindle hand wheel (not shown) of the lathe is then rotated to move the drum back and forth across the wheel 20 in the normal manner while slowly rotating the crossfeed wheel 26 to provide a smooth even finish on the brake surface.

As best shown in FIGS. 2 and 4, the power head 24 comprises a main housing member 30 to which a constant speed induction motor 31 is secured by means of a plurality of bolts 32. A pulley 33 is mounted on the shaft 34 of the motor 31 and is drivingly connected by a drive belt 35 to a spindle 36 suitably journaled in the housing by a pair of bearings 37 and 38. A generally spherical coupling 39 is provided at the distal end of the spindle 36 and extends into a cylindrical recess 40 at the forward end of the housing 30. A transverse hole 42 in the housing 30 partially intercepts the recess 40 and a locking pin 43 is disposed therein. The pin 43 has a tapered, flat surface 43a and a threaded end portion 44 on which a hand nut 45 is threaded for axially moving the locking pin 43 in the hole 42. A radial slot 46 is provided at the forward end of the housing 30 adjacent the recess 40 for angularly locating the quill assembly 22 relative to the power head 24.

The quill assembly 22 comprises a relatively heavy tubular member 48 having an end portion 49 which slidably fits in the recess 40 and a radially extending pin 50 receivable in the slot 46 to angularly position the quill assembly relative to the power head and to prevent relative rotation during the grinding operation. A circumferential groove 51 is provided in the end portion 49 for locking the quill assembly to the power head. A spindle 53 is .journaled in the forward end of the tube 48 in a pair of spaced apart bearings 54 and 55 and is fixedly connected at its rearward end to a tubular drive shaft 56. The drive shaft 56- has an internal diameter but slightly greater than the external diameter of the spherical coupling 39 which is received in the end thereof when the quill assembly is-secured to the power head. A drive plug 57 is fastened by a pin 58 in the end of the drive shaft 56 and has a diametrically disposed tongue 59 which fits into a diametrric slot 60 in the coupling 39. It will thus be seen that the shaft 56 is effectively journaled at one end by the bearings 54 and 55 and at the other end .by the bearings 37 and 38. Since a tubular shaft tends to be self aligning any misalignment of the spindles 36 and 53 is compensated for by the tubular shaft 56.

The forward end of the tube 48 is covered by a generally cup-shaped grit seal 60 which is held in place by a suitable retaining ring, and the grinding wheel is secured in the usual manner to the threaded distal end 61 1 of the spindle 53. In order to provide a flywheel effect for uniform rotation of the grinding wheel when hard spots are encountered, the spindle 53 is turned from solid bar stock and has an enlarged central portion 62 disposed between the bearings 54 and 55.

A grinding wheel guard 64 has an integral split collar 65 which fits over the tube 48 and is clamped thereto by a screw 66. The guard 64 has a hemispherical skirt 67 which extends forwardly over the grinding wheel 20.

In order to attach the quill assembly 22 to the power head 24, the hand nut 45 is loosened and pushed inwardly to axially move the tapered surface 43a of the locking pin 43 clear of the wall of the recess 40. The end 49 of the quill assembly is then inserted into the recess 40 and angularly oriented to position the pin 50 in the slot 46. It may be necessary to manually rotate the grinding wheel 20 to align the tongue 59 with the slot 60. The hand nut 45 is then tightened to move the tapered surface 43a of the locking pin into the circumferential groove 51. Quill assemblies 22 of different length are provided and are readily interchangeable in the power head for use with different sizes of brake drums.

While the present invention has been described in connection with a particular embodiment thereof, it will be understood that those skilled in the art may make many changes and modifications without departing from the true spirit and scope thereof. Accordingly, the appended claims are intended to cover all such changes and modifications as fall within the true spirit and scope of the present invention.

What is claimed is:

l. A grinder attachment for a lathe, comprising a power head including a housing and a motor,

a drive spindle journaled in said housing and connected to be driven by said motor,

said housing having an open socket into which one end of said spindle extends,

a quill assembly including a tubular body member and a driven spindle for carrying a grinding wheel journaled in one end of said body member,

the other end of said body member being removably and tightly securable to said housing around one end of said drive spindle,

a tubular drive shaft disposed in said tubular member in alignment with said spindles and with the ends of said drive shaft respectively connected to said spindles,

said spindles providing the sole support for the respective ends of said drive shaft,

said driven spindle having an enlarged intermediate portion disposed within the foreward end portion of said tubular body member, and

first and second bearing means respectively mounted at opposite ends of said enlarged portion for journaling said driven spindle in said tubular body member.

2. A grinder attachment according to claim 1,

wherein said one end of said drive spindle is generally spherical with the external diameter thereof slidably receivable in said drive shaft.

3. A grinder attachment according to claim 2, comprising a diametric slot in said one end of said drive spindle,

and

a coupling member fixedly mounted in said drive shaft and having a tongue receivable in said slot.

4. A grinder attachment according to claim 1 comprising manually operated means for locking and unlocking said tubular member in said socket.

5. A grinder attachment according to claim 4 wherein said means for locking comprises a circumferential groove in said tubular member, and

a transversely movable locking member mounted in said housing adjacent said socket for movement into and out of said groove when said tubular member is disposed in said socket.

6. A grinder attachment according to claim 5, comprising a radially extending pin on said tubular member, and

means defining in said housing adjacent to said socket a groove for receiving said pin for angularly orienting said quill assembly with respect to said power head. 

1. A grinder attachment for a lathe, comprising a power head including a housing and a motor, a drive spindle journaled in said housing and connected to be driven by said motor, said housing having an open socket into which one end of said spindle extends, a quill assembly including a tubular body member and a driven spindle for carrying a grinding wheel journaled in one end of said body member, the other end of said body member being removably and tightly securable to said housing around one end of said drive spindle, a tubular drive shaft disposed in said tubular member in alignment with said spindles and with the ends of said drive shaft respectively connected to said spindles, said spindles providing the sole support for the respective ends of said drive shaft, said driven spindle having an enlarged intermediate portion disposed within the foreward end portion of said tubular body member, and first and second bearing means respectively mounted at opposite ends of said enlarged portion for journaling said driven spindle in said tubular body member.
 2. A grinder attachment according to claim 1, wherein said one end of said drive spindle is generally spherical with the external diameter thereof slidably receivable in said drive shaft.
 3. A grinder attachment according to claim 2, comprising a diametric slot in said one end of said drive spindle, and a coupling member fixedly mounted in said drive shaft and having a tongue receivable in said slot.
 4. A grinder attachment according to claim 1 comprising manually operated means for locking and unlocking said tubular member in said socket.
 5. A grinder attachment according to claim 4 wherein said means for locking comprises a circumferential groove in said tubular member, and a transversely movable locking member mounted in said housing adjacent said socket for movement into and out of said groove when said tubular member is disposed in said socket.
 6. A grinder attachment according to claim 5, comprising a radially extending pin on said tubular member, and means defining in said housing adjacent to said socket a groove for receiving said pin for angularly orienting said quill assembly with respect to said power head. 